The present invention relates in general to circular weaving machines and, in particular, to a new and useful shedding device for such machines. The device of the invention utilizes a cam follower support which has cam means engaged in a rotating cam groove. The cam groove lies in a horizontal plane and, with its rotation, causes horizontal alternating movement of the cam follower support. Control rods are connected between the cam follower support and cranks. The cranks have arms which are connected to adjacent pairs of shedding rods of the circular weaving machine so that rotation of the cam groove causes reciprocal up and down movement of the shedding rods.
Circular weaving machines are different from other types of knitting machines which utilize hook needles to knit a fabric. Other knitting machines use a large number of hook needles which move alternately in a line. A circular weaving machine weaves a fabric utilizing horizontal yarns which are used in conjunction with the vertical yarns that are caused to make a shedding motion through which the vertical yarns pass. In other words, the horizontal yarns pass through loops of the vertical yarns when the vertical yarns are shed. The vertical yarns are shed by the motion of shedding rods. The vertical motion of the shedding rods is the same as the vertical motion needed for the vertical yarns.
In conventional circular weaving machines, the shedding rods each have a yarn guide (not shown) which guides a length of vertical yarn. The shedding rods are distributed in a circular path around the machine. Tappet rods are engaged with the shedding rods for moving the shedding rods up and down and, in turn, moving the lengths of yarn up and down. Several difficulties, however, have been discovered in such conventional circular weaving machines.
In a conventional circular weaving machine, a cam is provided with annular grooves. Each of the grooves receives a cam follower. The cam follower is located at one end of a lever arm. Each lever arm is pivotally mounted at a bearing post. Opposite ends of lever arms are connected to sliding guides or attachments 106 that are mounted on respective shedding rods. Cam is rotated by a motor and transmission means, to transmit an undulating path of cam grooves to the cam followers. This causes lever arms to pivot on bearing posts and transmit up and down movement to the shedding rods.
A shuttle for the horizontal yarns weaves the vertical yarns into a circular fabric which is drawn off the top of a circular weaving machine. Since a lever arm is provided for each of the shedding rods, the diameter of the circular fabric is limited by the number of shedding rods which can be distributed in a circle around the fabric in the machine. The capacity of the conventional circular weaving machine is thus limited by the fact that an equal number of lever arms and shedding arms must be used. The number of arms and rods can only be increased with difficulty. The lever arms move with a pivotal action and must be made sufficiently strong. They must also be made longer when larger circular fabrics are to be woven. The lever arms must be made strong to avoid fatigue and fractures in the material.
It is according difficult to enlarge the diameter of a circular fabric to be woven by a conventional circular weaving machine.